1. Field of the Invention
This invention relates to a flexible container for use in storage and transmission of a particulate material, a method of transmitting the particulate material from the flexible container by removing the particulate material out of the flexible container and transmitting the particulate material to a desired destination, an apparatus for executing this method in transmitting the particulate material from the flexible container, and a discharge unit for the flexible container which is used with this apparatus. More particularly, the invention relates to a flexible container, a method and apparatus for transmitting a particulate material from the flexible container, and a discharge unit for the flexible container, which enables transmission over a long distance or to a high location without scattering the particulate material to the ambient, and moreover, allow for low costs of the receiving equipment while avoiding an increase in volume and weight of the flexible container.
2. Description of the Prior Art
It is conventional practive, at a factory or the like handling a particulate material, to open bags containing stock powder and allow the powder to fall into a receiving hopper or a hopper of a processing apparatus in a first stage. This operation to fill the hopper, with the harmful particles of stock powder scattering to the ambient, is a hard, dirty and dangerous operation which pleases no worker. To avoid such scattering of stock powder to the ambient, a flexible container 100 as shown in FIG. 10, for example, is used as a container for transmitting stock powder today.
This flexible container 100 includes a main body 101 having a sealable input opening 102 formed in an upper portion thereof, and a discharge section 103 continuous from the lower end of the main body 101. This discharge section 103 is tied and sealed in an intermediate position thereof with a string 104 or the like. Then the discharge section 103 is turned up and bound with another string 105. In this state, a particulate material is introduced through the input opening 102, and thereafter the input opening 102 is sealed to be ready for storage or transportation.
At a receiving location, the string 105 binding the upturned discharge section 103 is unfastened and, as shown in FIG. 11, the lower end of the discharge section 103 is inserted into an input opening of a receiving hopper 107 of a particulate material transmitting apparatus 106. Alternatively, as shown in or FIG. 12, the lower end of discharge section 103 may be fitted over the input opening of the receiving hopper 107 and fastened thereto in a sealed condition. Subsequently, the string 104 closing the intermediate position of discharge section 103 is unfastened, and the stock powder in the flexible container 100 is allowed to fall into the receiving hopper 107. The stock powder is transmitted from a discharge unit 108 communicating with the lower end of receiving hopper 107, through a transmitting pipe 110 to a predetermined destination.
The particulate material transmitting apparatus 106 includes the receiving hopper 107, the discharge unit 108 connected to the lower end of the receiving hopper 107, a pressurized fluid source 109 for mixing a fluid under pressure into the particulate material in the receiving hopper 107 through the discharge unit 108, and the transmitting pipe 110 which receives, through the discharge unit 108, the particulate material having increased fluidity with the pressurized fluid mixed therein. A collecting device 111 is provided at the destination as necessary for collecting the particulate material separated from the pressurized fluid The particulate material collected in the collecting device is dropped into a receiving hopper of a particulate material transmitting apparatus in a second stage. The particulate material is transmitted from this receiving hopper to a collecting device of the particulate material transmitting apparatus in this stage. Then, the material is dropped into a relay hopper of a particulate material transmitting apparatus in a next stage or into the processing apparatus in the first stage.
However, the above method requires the receiving hopper 107 for receiving stock powder from the flexible container 100, which gives rise to a problem of increased cost of equipment at the receiving location.
In the conventional particulate material transmitting apparatus 106, the discharge section 103 comes off the receiving hopper 107 easily under increased transmitting pressure, and therefore the transmitting pressure cannot be raised above a certain fixed level. Consequently, the transmitting distance can be set to 10 meters at most, and the transmitting lift to 2 to 3 meters at most. The particulate material transmitting apparatus 106 must be installed in two to three stages between the receiving hopper 107 and the processing apparatus in the first stage which have a horizontal distance of 15 to 30 meters and a level difference of several meters to ten odd meters therebetween. This further increases the cost of equipment at the receiving location.
As a further problem, when the particulate material falls from the flexible container 100, with the lower end of discharge section 103 inserted into the input opening of receiving hopper 107 as shown in FIG. 11, fine particles fly from between the receiving hopper 107 and the input opening of discharge section 103 to scatter to the ambient.
Where, as shown in FIG. 12, the lower end of the discharge section 103 of flexible container 100 is bound to the outer peripheral surface of the input opening of receiving hopper 107, the particulate material becomes lodged between the lower end of flexible container 100 and the input opening of receiving hopper 107. This gives rise to a problem that this particulate material scatters to the ambient when the flexible container 100 is removed from the receiving hopper 107 after a material dropping operation.
In addition, the peripheral edge of the opening in the lower end of flexible container 100 is simply tied to the receiving hopper according to this method. Therefore, with an increase in the transmitting pressure of the particulate material transmitting apparatus 106, the flexible container 100 becomes loose from the receiving hopper 107, whereby the stock powder in the flexible container 100 scatters to the ambient.
To solve this problem, a special flexible container has been marketed in recent years. In place of the discharge section, a tub-like palette formed of a synthetic resin is connected to the lower end of the main body of the flexible container. A pressurized fluid is introduced under pressure into the main body through this palette to increase the fluidity of the particulate material. The particulate material is taken out of the main body by causing it to fall to a discharge gate provided on a lateral surface of the palette, or by blowing it up through an exhaust opening formed at the upper end of the main body (Semi-Bulk Systems, Missouri, U.S.A.; product name: Air Palette System).
According to this special flexible container, the receiving hopper and the discharge unit of the particulate material transmitting apparatus may be omitted from the receiving location, which allows a reduction in the cost of equipment at the receiving location. Moreover, the discharge gate and/or exhaust opening can be sealed with a self-closing coupling, for example. Thus, a transmitting pipe can be connected and disconnected with little possibility of scattering fine particles to the ambient.
However, since this flexible container has the synthetic resin palette connected to a lower position thereof, a large space is occupied whether filled with a particulate material or in a tare state. This poses a problem of increasing storage and transmission costs.
The flexible container itself is expensive because of the palette provided for the bottom of the flexible container. Considering the cost of the flexible container itself, and the increased costs such as the storage cost and transmission cost, a problem may be found in its practicability.